Small‐scale mutations in the gene encoding the Runt‐related transcription factor 2 (RUNX2), which plays a role in osteoblast and chondrocyte maturation, are identified in approximately 60% of CCD patients, whereas copy‐number variants (CNVs) in the same gene are responsible for approximately 10% of CCD cases.(14) However, the rest of the CCD patients remain without a genetic diagnosis. This evidence concerns the gene RUNX2 and cleidocranial dysplasia 1.